Default Route and MPLS

Hi,

 

I have an MPLS VPN network within our internal network and there's just one weird behavior with the trace route when passing through the MPLS network.

 

My network looks like this, PE1-----P1-------P2------PE2. P1 and P2 are 6504-E running 12.2(33)SXI8.

 

PE1 and PE2 runs MPLS VPN and the rest is just normal. I have networks under P1 that are not MPLS enabled. So they are all just pop tag or no tag at all. I also do have internal subnets under P2.

 

P2 has an internet connection as well. Default route is being learned via iBGP from our internet router. The BGP learned default route was redistributed to EIGRP so P1 learned the default route as EIGRP EX with P2 as the next hop.

 

If I conduct a trace route from the networks under P1 that are not MPLS enabled, I can see P1 as the first hop, P2 disappeared, then the 3rd hop would be the internet router. After few hours of troubleshooting, What I did is to establish eBGP connection between P2 and P1 to learn the default route via BGP instead of EIGRP EX. After that, the trace went fine! I configured static route as default route then poof, P2 disappeared again from the trace.

 

On a different site;

 

I have P3 connected to both P1 and P2. P3 is also 6504-E/12.33(SXI8). P3 is using a static default route instead of the EIGRP EX. The default route points to P2 since the internet gateway is out there. Same thing, subnets under P3 without MPLS enabled loses hop 2 or P2 on the trace and the rest can be seen up to the last hop. I established eBGP peering between P2 and P3 for default route, again, trace route went ok.

 

Same scenario again, different site.

 

This time, we have P4. Connected to P1 and P2 again. The P4 router is 3800. Default route is via static pointing to P2. Trace route is ok coming from the networks under 3800 with no MPLS enabled. The hop between P4 and P2 can be seen.

 

Have any idea why this is happening? P4 and P3 uses the same setup but different results. That's the first weird thing. The only difference is the hardware.

 

Next, P1 and P3 experienced the same thing, the link between P1/P3 and P2 can only be seen if BGP was the default route.

 

Thanks.